Effect of Gaze Angle During the Vertical Video Head Impulse Test Across Two Devices in Healthy Adults and Subjects With Vestibular Loss.
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ABSTRACT: Objective
To evaluate the effect of gaze angle on vertical vestibulo-ocular reflex (VOR) gain using two different video head impulse (vHIT) devices in healthy adults and subjects with bilateral vestibular loss (BVL).Study design
Prospective study.Setting
Hospital research laboratory.Subjects
Twenty-four healthy adults (mean [standard deviation {SD}] age = 32 [4.8]; 23-42; 8 men) and four subjects with previously diagnosed BVL (mean age [SD] = 32 [8.2]; 21-40; 3 men) participated.Intervention
Vertical canal vHIT was administered with two different devices using three gaze angles (-45 degrees, 0 degree, +45 degrees). These devices have different gain calculation algorithms and different head and gaze angle protocols.Main outcome measures
Vertical canal gain and presence or absence of reset saccades.Results
A significant stepwise reduction in vHIT gain was noted as gaze moved away from the plane of the canals stimulated (from -45 degrees to 0 degree, to +45 degrees) for both healthy adults and subjects with BVL. vHIT gain was able to separate the two groups using gaze angles -45 degrees and 0 degree.Conclusions
In spite of their differences in gain algorithm and recommended head position and gaze angle, each device was able to appropriately separate healthy adults from subjects with BVL with high sensitivity/specificity.
SUBMITTER: Patterson J
PROVIDER: S-EPMC7311278 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:ObjectiveWhile compensatory saccades indicate vestibular loss in the conventional head impulse test paradigm (HIMP), in which the participant fixates an earth-fixed target, we investigated a complementary suppression head impulse paradigm (SHIMP), in which the participant is fixating a head-fixed target to elicit anticompensatory saccades as a sign of vestibular function.MethodsHIMP and SHIMP eye movement responses were measured with the horizontal video head impulse test in patients with unilateral vestibular loss, patients with bilateral vestibular loss, and in healthy controls.ResultsVestibulo-ocular reflex gains showed close correlation (R(2) = 0.97) with slightly lower SHIMP than HIMP gains (mean gain difference 0.06 ± 0.05 SD, p < 0.001). However, the 2 paradigms produced complementary catch-up saccade patterns: HIMP elicited compensatory saccades in patients but rarely in controls, whereas SHIMP elicited large anticompensatory saccades in controls, but smaller or no saccades in bilateral vestibular loss. Unilateral vestibular loss produced covert saccades in HIMP, but later and smaller saccades in SHIMP toward the affected side. Cumulative HIMP and SHIMP saccade amplitude differentiated patients from controls with high sensitivity and specificity.ConclusionsWhile compensatory saccades indicate vestibular loss in conventional HIMP, anticompensatory saccades in SHIMP using a head-fixed target indicate vestibular function. SHIMP saccades usually appear later than HIMP saccades, therefore being more salient to the naked eye and facilitating vestibulo-ocular reflex gain measurements. The new paradigm is intuitive and easy to explain to patients, and the SHIMP results complement those from the standard video head impulse test.Classification of evidenceThis case-control study provides Class III evidence that SHIMP accurately identifies patients with unilateral or bilateral vestibulopathies.
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Project description:Background and objectiveMigraine is an extremely prevalent primary headache disorder that frequently associates parallel symptoms such as dizziness, tinnitus and hearing loss. Our aim is to investigate differences in video head impulse (vHIT) results with patients suffering from vestibular migraine (VM) and healthy people, taking into consideration mean values of vestibule ocular reflex (VOR) gain, occurrence of the compensatory saccades latency and amplitude. According to the results, determine the usefulness of vHIT in vestibular migraine diagnostics.MethodsA total number of 120 subjects were enrolled in the study, 80 of them were vestibular migraine patients (VM), while the other 40 were a control group of age matched healthy subjects. History was taking during the evaluation; videonystagmography and the video head impulse test were done.ResultsThe rate of saccades is much more higher in the VM group compared to the healthy subjects group, only 7.5% of the VM group showed a low VOR gain with compensatory saccades denoting a vestibular deficit.ConclusionThe refixation saccades are an important sign that could underlie different vestibular problems. vHIT result can contribute to the completion of full mosaic of vestibular migraine diagnostics.
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Project description:ObjectiveTo determine the accuracy of the bedside head impulse test (bHIT) by direct comparison with results from the quantitative head impulse test (qHIT) in the same subjects, and to investigate whether bHIT sensitivity and specificity changes with neuro-otological training.MethodsVideo clips of horizontal bHIT to both sides were produced in patients with unilateral and bilateral peripheral vestibular deficits (n = 15) and in healthy subjects (n = 9). For qHIT, eye and head movements were recorded with scleral search coils on the right eye and the forehead. Clinicians (neurologists or otolaryngologists) with at least 6 months of neuro-otological training ("experts": n = 12) or without this training ("non-experts": n = 45) assessed video clips for ocular motor signs of vestibular deficits on either side or of normal vestibular function.ResultsOn average, bHIT sensitivity was significantly (t test: p<0.05) lower for experts than for non-experts (63% vs 72%), while bHIT specificity was significantly higher for experts than non-experts (78% vs 64%). This outcome was a consequence of the experts' tendency to accept bHIT with corresponding borderline qHIT values as still being normal. Fitted curves revealed that at the lower normal limit of qHIT, 20% of bHIT were rated as deficient by the experts and 37% by the non-experts.ConclusionsWhen qHIT is used as a reference, bHIT sensitivity is adequate and therefore clinically useful in the hands of both neuro-otological experts and non-experts. We advise performing quantitative head impulse testing with search coils or high speed video methods when bHIT is not conclusive.
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Project description:BackgroundThe head impulse test (HIT) is a useful bedside test to identify peripheral vestibular deficits. However, such a deficit of the vestibulo-ocular reflex (VOR) may not be diagnosed because corrective saccades cannot always be detected by simple observation. The scleral search coil technique is the gold standard for HIT measurements, but it is not practical for routine testing or for acute patients, because they are required to wear an uncomfortable contact lens.ObjectiveTo develop an easy-to-use video HIT system (vHIT) as a clinical tool for identifying peripheral vestibular deficits. To validate the diagnostic accuracy of vHIT by simultaneous measures with video and search coil recordings across healthy subjects and patients with a wide range of previously identified peripheral vestibular deficits.MethodsHorizontal HIT was recorded simultaneously with vHIT (250 Hz) and search coils (1,000 Hz) in 8 normal subjects, 6 patients with vestibular neuritis, 1 patient after unilateral intratympanic gentamicin, and 1 patient with bilateral gentamicin vestibulotoxicity.ResultsSimultaneous video and search coil recordings of eye movements were closely comparable (average concordance correlation coefficient r(c) = 0.930). Mean VOR gains measured with search coils and video were not significantly different in normal (p = 0.107) and patients (p = 0.073). With these groups, the sensitivity and specificity of both the reference and index test were 1.0 (95% confidence interval 0.69-1.0). vHIT measures detected both overt and covert saccades as accurately as coils.ConclusionsThe video head impulse test is equivalent to search coils in identifying peripheral vestibular deficits but easier to use in clinics, even in patients with acute vestibular neuritis.
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Project description:ObjectivesVirtual reality (VR) offers an ecological setting and the possibility of altered visual feedback during head movements useful for vestibular research and treatment of vestibular disorders. There is however no data quantifying vestibulo-ocular reflex (VOR) during head impulse test (HIT) in VR. The main objective of this study is to assess the feasibility and performance of eye and head movement measurements of healthy subjects in a VR environment during high velocity horizontal head rotation (VR-HIT) under a normal visual feedback condition. The secondary objective is to establish the feasibility of VR-HIT recordings in the same group of normal subjects but under altered visual feedback conditions.DesignTwelve healthy subjects underwent video HIT using both a standard setup (vHIT) and VR-HIT. In VR, eye and head positions were recorded by using, respectively, an imbedded eye tracker and an infrared motion tracker. Subjects were tested under four conditions, one reproducing normal visual feedback and three simulating an altered gain or direction of visual feedback. During these three altered conditions the movement of the visual scene relative to the head movement was decreased in amplitude by 50% (half), was nullified (freeze) or was inverted in direction (inverse).ResultsEye and head motion recording during normal visual feedback as well as during all 3 altered conditions was successful. There was no significant difference in VOR gain in VR-HIT between normal, half, freeze and inverse conditions. In the normal condition, VOR gain was significantly but slightly (by 3%) different for VR-HIT and vHIT. Duration and amplitude of head impulses were significantly greater in VR-HIT than in vHIT. In all three altered VR-HIT conditions, covert saccades were present in approximatively one out of four trials.ConclusionOur VR setup allowed high quality recording of eye and head data during head impulse test under normal and altered visual feedback conditions. This setup could be used to investigate compensation mechanisms in vestibular hypofunction, to elicit adaptation of VOR in ecological settings or to allow objective evaluation of VR-based vestibular rehabilitation.
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Project description:Introduction We are now able to detect abnormalities for any semicircular canal with the use of the video head impulse test (vHIT). Prior to the vHIT, the gold standard for unilateral canal paresis of the lateral canal was considered the caloric test. Clinical cases where the caloric test and vHIT are discordant are not uncommon. Methods Retrospective study. All consecutive cases of dizziness seen from 11/2020 to 12/2021 for which the patient underwent both caloric and vHIT tests performed within 10 days, were reviewed. Patients with discordant results were included. We evaluated the caloric response, vHIT gains for all canals and saccades, with and without gain abnormalities. Results We included 74 cases of dizziness with dissociated results. The most common finding was a normal caloric response with abnormal vHIT results (60.8%); the main abnormal finding on vHIT was the presence of saccades. In this group, 37.7% of patients had normal gains and refixation saccades. In addition, the most found low gain was for the posterior canal. The main diagnosis in this group was vestibular migraine. For the group with unilateral caloric paresis and normal vHIT gain in the lateral canal, the main diagnosis was Ménière's disease. Discussion The most common disorders with discordant results were Ménière's disease and vestibular migraine. The caloric test and vHIT are complementary and combining both tests provide greater clinical information. Further research is needed to understand refixation saccades with normal gains.
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Project description:BackgroundWe propose a Suppression Head IMPulse (SHIMP) test method that provides for equipment only through the use of InfraRed Video-OculoScopy (IR-VOS) and allows horizontal and vertical semicircular canal function evaluation in bedside mode. We therefore named the test InfraRed clinical SHIMP (IR-cSHIMP).MethodsTo check IR-cSHIMP diagnostic efficiency, we studied 22 normal subjects, 18 patients with unilateral, and 6 with bilateral deficient vestibulopathy. Each subject first underwent a vestibular examination and, only later, an IRc-SHIMP test.ResultsWhen the IR-cSHIMP test was performed in the horizontal plane, all normal subjects showed anti-compensatory saccades. When the vertical semicircular canal function was evaluated, the same result was obtained in all normal subjects except three, which were considered false positives. In patients with vestibular deficits, the test performed in the horizontal and vertical planes were always pathological, with 100% agreement between clinical and instrumental tests.ConclusionsOur bedside method proved to be fast, simple, and effective in discriminating between healthy and pathological subjects. It required only the same skill as the better-known cHIT. For these reasons, we believe that the IR-cSHIMP should be part of daily clinical practice as a useful tool in the selection of patients to undergo more sophisticated investigations.
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